The 3D shells k-space trajectory using in magnetic resonance imaging (“MRI”) divides k-space into a series of concentric shells and samples each one using 3D helical readouts. With the shells trajectory, the inner k-space, which determines the image contrast, can be efficiently sampled within several interleaves, making it a maximally centric 3D acquisition. The acquisition of inner shells can be synchronized with the time when a certain desired image contrast is expected, such as the contrast agent arrival time in gadolinium-enhanced magnetic resonance angiography, or when the peak of white-to-gray-matter contrast is achieved after a magnetization preparation (“MP”) radio frequency (“RF”) pulse.
Partial Fourier (“PF”) homodyne acquisition is a commonly-used acceleration technique in Cartesian MRI that exploits the conjugate symmetry of k-space measurements. However, unlike Cartesian MRI, utilizing homodyne acquisition in non-Cartesian acquisitions is not straightforward, since directly applying homodyne acquisitions in a direction sampled with a non-Cartesian trajectory does not always yield a physically-achievable trajectory (e.g., 2D spiral), or an iterative reconstruction may be required.